The invention relates to an apparatus for manufacturing a thermoplastic container with a handle. The opening for the hand is formed by joining two opposite walls of the container. The apparatus includes a mechanism for providing a hose-like parison and includes a forming die consisting of substantially two mold halves which may preferably be coolable. The apparatus further includes means for creating the void in the container which creates the handle and these means include plungers that may be moved into the interior volume of the parison from either side. The parison may be formed as a hose or may be injection molded.
The invention relates primarily to containers with handles of the type used for common household applications, for example, for holding laundry or dishwashing materials. The openings for the hand are not usually of constant cross-section, i.e., the size of the opening decreases from the outside of the container toward the vertical symmetry plane. In addition, the molds generally taper in the direction of both their ends.
For producing containers of this type with a handle in an extrusion process, it is known to take a hose with a large diameter in relation to the interior of the blow mold so that the hose is capable of being flattened by by together the two halves of the mold so that its width will be substantially that of the finished article. Thus, as viewed perpendicular to the plane of separation between the two blow mold halves, the hose-like parison extends everywhere beyond the parts of the mold which extend into the interior voids so that the recess to be formed between the handle and the rest of the container is covered by plastic material. In this manner the hose-like parison is clamped by these mold parts and also by the interior surface of the associated molding region. In the subsequent blow molding, the hose is blown up everywhere, i.e., also around this part of the mold. When the blow molding process is terminated and the article is removed, the squeezed portion, which consists of two layers of hose, is knocked out. This apparatus and the associated process has the substantial disadvantage that when the blow mold is closed, the portions of the hose which first come in contact therewith are prematurely cooled off and thus, during the subsequent blow molding, the material is expanded unevenly so that the final container has varying wall thickness.
In another apparatus (Swiss Pat. No. 542,700) the hose is first made into an intermediate parison without a handle whose outside dimensions are smaller than those of the final article but large enough so that, when it is inserted into a second blow mold for being formed into the final container, those portions of the parison which extend into the interior of the mold and are to form the recess between the handle and the container are definitely grasped when the mold halves are closed and the container is thus pinched in this location. The drawback of this apparatus is that it is very expensive and that the process associated therewith is complicated and time-consuming.